Is there any benefit to switching to dot 5 fluid instead of using dot 4? I am installing braided brake lines and have to flush the brake system anyway, so I thought I would use dot5, which is synthetic.
Nope, it's not compatible with DOT 3 or 4, which your system calls for. Get the Motul RBF 600. I think that's the name, it's Motul DOT 4 racing fluid that lots of us use and like.
DOT 5.1 is compatible with DOT 3 & 4, but not DOT 5.
Dot 5 is silicone based and completely different. It is usually used on show car that are hardly used due to it's ability to not draw in water like dot 3 & 4. It can be left in a reservoir for long periods of time without damage. But it is spongy because of the silicone. :nono:
I was once told that unless your brake system was specifically designed to use DOT 5, that it would eventually deteriorate the seals = leakage = no brakes. I don't know if that is true or not.
We know Dot 5 is incompatible with other brake fluids.
Dot 5.1 IS compatible with 3 and 4.
Now for the bit of trivia that prompted me to post. I was in need of some brake fluid so I could get a nice ride in before the next Monday, but I missed my local Honda parts department Saturday closing at noon by 10 minutes. Having searched all the local autoparts stores for DOT 4 before, and finding only one local shop had it (for exotics!) that was my only hope but I knew it also was closed.
Out of desperation I went into the Harley dealership. I'd never been there before and looked around with awe at all the Harley stuff for sale. There were even a couple Harleys and several Buells on the floor as well. I feigned club membership by looking at a VRod for a bit, and then I stood for ten minutes getting to the parts counter (there were a lot of people ahead of me, and there were three guys working the counter. Geez, I guess Harley owners need a lot of parts!)
Anyway, I get to have my turn and asked for some DOT 4 fluid and the guy just gave me a 15 second moment of silence while looking at me as if I were some sort of deranged alien being. Then he said they didn't carry it. "All Harleys use DOT 5. Didn't you know that????"
Suddenly feeling surrounded by tee shirt and vest shoppers, and very alone in uncharted territory I said "Er, no I didn't. Not that I doubt you, but I want to check my owner's manual before I buy some. Thanks, and have a great day!"
I then beelined it for the door and left the area post haste.
Yup, all Harleys are dot 5, thats pretty much the only reason it is available commertialy. With the exception of some european cars, no commertial manufactures use dot 5. The military uses it, but thats more for meeting Artic Weather specs.
Hogs use it because DOT5 dosent eat paint like the others do. Now you know where their priority lies........
Besides being incompatible the other downside to DOT5 is that it is not hygroscopic like the others. In other words, any water that gets in the system(its not a perfect seal you know) puddles in the low spots of the system and corrodes. Its NOT easy to get rid of this as regular bleeding is done at the 'high' points of the system.
I was in Europe on a bike holiday and due to a catalogue of errors at the bike shop, the mechanic had changed the brake pads fro me but not bled the brakes. They got progressively worse through the trip. One morning the brake lever came back to the bar and I had to do something!!!!!
The only dealer I could find in the middle of nowhere only had dot 5. I had to use it to bleed the brakes as I had no brakes.
Yes it certainly is spongy. Yes it is blue. And yes I don't like it.....now I'm back home it is coming straight out again
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